Department of Integrative Bioscience and Biotechnology, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul, 143-747, South Korea.
Korea Food Research Institute, Wanju-gun, Jeollabuk-do, 55365, South Korea.
Biochem Biophys Res Commun. 2022 Aug 20;617(Pt 1):48-54. doi: 10.1016/j.bbrc.2022.05.098. Epub 2022 Jun 1.
We previously demonstrated that kaempferol, a flavonoid present in various herbs, inhibits adipogenesis by repressing peroxisome proliferator-activated receptor γ (PPARγ) activity. Here, we focused on elucidation of the underlying mechanism using genome-wide tools. First, RNA sequencing (RNA-seq) analysis showed downregulation of genes involved in adipogenesis in response to kaempferol. Subsequent ChIP assays revealed that kaempferol regulates the expression of adipogenic (Adipoq, Fabp4, Lpl) genes by modulating enrichment of active H3K4me3 and repressive H3K27me3 histone codes on target promoters. Second, we performed ChIP sequencing analysis of active H3K4me3, and co-analysis with RNA-seq identified PPARγ responsive sites in genes downregulated by kaempferol, in terms of expression and H3K4me3 deposition. Third, direct kaempferol binding to PPARγ, for which the K value was 44.54 μM, was determined by microscale thermophoresis. Further RT-qPCR and GST pull-down assays demonstrated that kaempferol antagonizes rosiglitazone-induced PPARγ activation and impairs the rosiglitazone-dependent interaction between PPARγ and its coactivator CBP. Overall, our data suggest that kaempferol, as a PPARγ antagonist, mediates epigenetic repression of lipid accumulation by regulating histone methylation, and could serve as a candidate epigenetic drug to treat obesity-related diseases.
我们之前证明，存在于各种草药中的类黄酮山柰酚通过抑制过氧化物酶体增殖物激活受体 γ (PPARγ) 的活性来抑制脂肪生成。在这里，我们使用全基因组工具重点阐明了潜在的机制。首先，RNA 测序 (RNA-seq) 分析显示，山柰酚响应下调了与脂肪生成相关的基因。随后的 ChIP 实验表明，山柰酚通过调节靶启动子上活性 H3K4me3 和抑制性 H3K27me3 组蛋白密码的富集来调节脂肪生成（Adipoq、Fabp4、Lpl）基因的表达。其次，我们对活性 H3K4me3 进行了 ChIP 测序分析，并与 RNA-seq 的联合分析确定了山柰酚下调的基因中受 PPARγ 调控的响应位点，从表达和 H3K4me3 沉积两方面来看。第三，通过微量热泳动确定了山柰酚与 PPARγ 的直接结合，其 K 值为 44.54 μM。进一步的 RT-qPCR 和 GST 下拉实验表明，山柰酚拮抗罗格列酮诱导的 PPARγ 激活，并损害罗格列酮依赖的 PPARγ 与其共激活因子 CBP 之间的相互作用。总的来说，我们的数据表明，山柰酚作为一种 PPARγ 拮抗剂，通过调节组蛋白甲基化介导脂质积累的表观遗传抑制，可作为治疗肥胖相关疾病的候选表观遗传药物。
